A LITTLE GOES A LONG WAY

Hi,
What does “A LITTLE GOES A LONG WAY” mean? Thank you.
If they want to ban Marmite, that’s fine by me. Yes of course it’s tasty, in small doses, but isn’t there something inherently WRONG about something of which A LITTLE GOES A LONG WAY? If it’s so great, why would you have to SPREAD THINLY?

A small amount lasts for a very long time. (Nt in terms of age, but in terms of the amount you use of it)

In this case a small jar of Marmite lasts for a very long time because you are expected to spread it thinly on your toast/crackers, so you won’t use much of it per serving - most people don’t like the taste at all if it is layered on thickly.

(…and of course, some of us can’t stand the taste, no matter how thinly it is spread!)